ABSTRACT Spontaneous pneumomediastinum is considered an uncommon entity in children, with highly variable incidence. In childhood it is associated with asthmatic crises and respiratory tract infections, trauma, vomiting, intense exercise, anxiety with hyperventilation, and drug use. We present a case report of a previously healthy 5-year old who suddenly developed respiratory distress and subcutaneous emphysema and who presented at the Emergency Department, leading to a diagnosis of spontaneous pneumomediastinum. Our purpose is to highlight the causes and differential diagnoses that should be considered when presented with a patient with these characteristics in an emergency department.